To write a great lime - meaning fanfiction, research is key. Look at how other successful fanfiction writers in the same genre handle similar situations. In addition, create a believable scenario for the characters to interact in this way. If it's a historical - based fanfiction, make sure the social norms of that time are considered. And don't rush the story. Let the lime - meaning interactions develop naturally over the course of the narrative, building up the anticipation for the readers.
When writing a lime - meaning fanfiction, you need to be aware of the boundaries. It should be more about the suggestion of something romantic or a bit more than platonic rather than being explicit. Use descriptive language to convey the mood. For instance, describe how a character's cheeks turn a bit red when the other is close, or how their heart races. Also, focus on the emotional connection between the characters as much as the physical signs of attraction.